Method and means for mixing a mass of concrete or other material



Nov. 25, 1969 E. v. FEJMERT METHOD AND MEANS FOR MIXING A MASS OF CONCRETE OR OTHER MATERIAL Filed Nov. 6, 1967 V W F HI] I I 1 lNvENToIa EBlK VALDEMAR FEJMERT United States Patent Int. 01. msc 5/06, 7/14 US. Cl. 259-147 6 Claims ABSTRACT OF THE DISCLOSURE The mixing of concrete in a flat-bottomed mixing tank by the action of power-driven paddles in which fluid is injected at a selected temperature and pressure into the mass of material being worked by the paddles.

The invention relates to a method and means for mixing concrete, mortar and other materials in a fiat-bottomed mixing tank with an upright peripheral wall, which may be cylindrical, and in some cases a coaxial upright inner wall, defining a mixing space through which paddles are driven to effect the mixing.

The admission of humidity for attaining a desired consistency of the mass of material to be mixed in the manufacture of concrete is usually accomplished by dumping a previously measured quantity of water directly on the materials in the mixing tank from above, but this results in the often great amount of water which is used impinging on the upper layer of the mass and causing soaking and separation of the constituents of the mass. Also the even distribution of the humidity in the mass cannot be obtained until the water has worked down towards the bottom, and around the mixing space where the paddles are working. Moreover, the consistency of the mass cannot be properly measured by reference to the quantity of water added, because of the variable amount of moisture already held by the materials, especially when they are stored in the open air.

In particular, the manufacture of concrete in wintertime requires an adequate heating of the water before it can be dumped upon the frosty materials in the mixing tank, and this gives rise to the further disadvantage that there is a risk of local overheating. There is also the risk that the heating effect of the water will be'considerably reduced by the slowness with which it spreads through the mass, and this causes uneven, and inadequate heating of the mass. Furthermore, before the water has penetrated to the bottom of the mixing tank, the paddles will 'have to work in the mass when it is dry, and this results in severe wear of the paddles and the bottom of the tank.

The object of the invention is to mitigate these various disadvantages.

According to the invention the method of mixing concrete, mortar or other materials in a fiat-bottomed mixing tank with an upright peripheral wall defining a mixing space through which paddles are driven to effect the mixing, which involves injecting fluid, at a selected temperature and pressure, through the upright wall in spaced positions around its periphery, into the mass of material being worked by the paddles. In this manner penetration of the mass of material by the fluid is facilitated.

According to a further feature, and in the case where the mixing space is made annular by having its inner periphery defined by a second and coaxial upright wall of the tank, the method also involves injecting the fluid through the second upright wall in spaced positions around its periphery into the mass of material being worked by the paddles. Thus, the penetration by the fluid "ice is still further facilitated by injecting it into the mass of material from both sides of the annular mixing space.

Although the injection of the fluid can be effected at more than one level into the mass of material it is preferred to effect it only at a level which is just above that of the flat bottom of the tank.

The fluid to be injected can be water or steam.

As the bottom and the lower parts of the upright walls of the mixing tank can be flushed with the moisture, as the materials are charged into the mixing tank, a lubrieating film will occur which eonsiderablyreduces the wear of the tank and paddles.

An estimation of the grade of moisture of the batch can be achieved by this method as the variation of the consistency of the mixture is in a certain degree proportional to the injection pressure of the moisture, and this can be established by means of electronic measurement.

The injection of the fluid can also be used for cleaning the mixing tank when empty.

The invention also includes a mixing apparatus for performing the above method, and according to a still further feature of the invention it comprises apparatus including a fiat-bottomed mixing tank with an upright peripheral wall defining a mixing space through which paddles are driven to effect the mixing, a plurality of jets extending through the (or each, as appropriate) upright wall in spaced positions around its periphery, and pipes for supplying fluid at a selected temperature and pressure to the jets so that the latter inject the fluid into the mass of material being worked by the paddles.

The apparatus, according to yet another feature, has the jets mounted in recesses in the angles between the bottom wall and the (or each, as appropriate) upright wall.

In the accompanying drawings:

FIGURE I is a diagrammatic vertical section through one form of apparatus for performing the method;

FIGURE II is a section on the line AA of FIGURE I; and

FIGURE III is a section on the line B-B of FIGURE I showing one of the jets for the injection of the fluid.

Referring to the drawings, the tank 1 has a flat bottom 1a and an upright outer peripheral wall 1b which is preferably cylindrical. The bottom 1a also supports an upright inner peripheral wall 2 coaxially within wall 1b, and this inner wall is also preferably cylindrical so as with the outer wall to define an" annular mixing space. The inner wall 2 supports through bearings a rotatable member 3 which is driven in any suitable way and supports arms 4 carrying paddles 5 for mixing a charge of material placed in the mixing space. As thus far described the machine is of a known type.

In accordance with the invention pipes 6, for supplies of fluid (e.g., water or steam, or both) are arranged around the outside of the outer wall 1b and the inside of the inner wall 2, and are connected to nozzles 7 for delivering jets of the fluid in both directions across the annular mixing space. These jets, as shown, are divergent so that they cover the whole area of the mixing space.

The nozzles 7 are arranged in the angles between the bottom la of the tank and its upright walls 1b and 2, and may be formed in rings 8 suitably held in position.

The pipes 6, which are shown as being of rectangular cross-section, are provided with a circumferential baflle 9 to ensure that fluid delivered to the pipes at 10 shall not enter the nozzles by dynamic pressure but solely due to the static pressure it develops in the pipes.

The nozzles can be controlled individually by means (not shown) and the number of them to be used can be adapted to the desired period for the injection of the water to take place, and in relevant cases for the steam to flow attaining the desired temperature of the concrete.

Simultaneously with the injection of the moisture, cement, quicklime etc. may be injected into the mass in the same way in order to obtain a swift, even and dust free spreading of those materials in the mass.

What I claim as my invention and desire to secure by Letters Patent of the United States is:

1. Apparatus for mixing concrete, mortar or like material by agitating the material whilst injecting fluid into the material from a position below the surface of the material, wherein the improvement comprises a mixing tank having a flat bottom and an upright Wall defining a mixing space, paddles supported to be driven through the mixing space to effect the mixing of material, a plurality of nozzles extending through the upright wall adjacent the flat bottom below the surface of the material, said nozzles spaced in positions around the periphery of the upright wall to inject fluid directly into the mass of the material being worked by said paddles, and pipes for supplying said. fluid to said nozzles.

2. Apparatus according to claim 1 including an annular fillet member in the corner between the flat bottom and the lower end of the upright wall, said annular fillet member defining said nozzles.

3. Apparatus for mixing concrete, mortar or like material by agitating the material whilst injecting fluid into the material from a position below the surface of the material, wherein the improvement comprises a mixing tank with a flat bottom and first and second coaxial upright walls defining a mixing space, paddles supported to be driven through the mixing space to effect the mixing of material, a plurality of nozzles extending through both said upright walls adjacent the flat bottom below the surface of the material, said nozzles spaced in positions around the periphery of each upright wall to inject fluid directly into the mass of material being worked by said paddles, and pipes for supplying said fluid to said nozzles.

4. Apparatus according to claim 3 including annular fillet members in the corners between the flat bottom wall and the lower end of the upright Walls, said annular fillet members defining said nozzles.

5. A method of mixing concrete, mortar or like material by agitating the material Whilst injecting fluid into the materialfrom a position below the surface of the material to ensure substantially even distribution of the fluid throughout the material, wherein the improvement comprises injecting steam into the material.

6. A method of mixing concrete, mortar or like material by agitating the material whilst injecting fluid into the material from a position below the surface of the material to ensure substantially even distribution of the fluid throughout the material, wherein the improvement comprises injecting solid material of fine particle size into said material together with said fluid.

References Cited UNITED STATES PATENTS 1,459,657 6/1923 Dempsey 259-468 3,081,983 3/1963 Thibodeaux 259178 3,168,296 2/1965 Cowley 259178 3,188,059 6/1965 Strong 25'9179 ROBERT W. JENKINS, Primary Examiner US. Cl. X.R. 

